Some recent development efforts associated with monitoring the media consumption behaviors of individuals have been directed toward personal portable meters (PPM's) or portable media monitors. In contrast to the relatively stationary media metering devices used with more traditional media monitoring systems, PPM's are carried by monitored individuals or panelists as they engage in their regular daily activities, including media consumption activities. For example, each panelist may attach a PPM to their clothing (e.g., to a belt or waist portion of their pants) and may move freely about their home and, in some cases outside their home, while wearing (or at least carrying) the PPM.
As a person or panelist travels with their PPM throughout their household and outside their household, the PPM receives media signals such as, for example, audio and/or video content information provided by media delivery devices (e.g., televisions, radios, etc.) distributed throughout the household. The media signals received by the PPM may be encoded to facilitate subsequent identification of the audio/video content or programs and/or the PPM's may be configured to use signature generation techniques to identify audio/video content or programs received by the PPM's. Each person's PPM may receive a media signal or signals (i.e., different audio/video content) based on their unique location and their location relative to the one or more media delivery devices to which they and their PPM are exposed.
To measure media consumption, many PPM's are configured to capture identification codes that have been embedded in the audio signals associated with television programs, radio programs, etc. These codes, which are often referred to as ancillary codes, may be captured or extracted by a PPM and later transmitted to a central data processing facility that uses the codes to identify the programming that was consumed (e.g., viewed, listened to, etc.) and to properly credit that consumption to the appropriate programs. The portable nature of PPM's enables these devices to be used to measure media consumption activities that occur both inside the home and outside the home. Although PPM's have some advantages and capabilities that otherwise stationary metering devices do not, the code detection capabilities of many known PPM's are limited.
In a typical household there are often multiple media delivery devices and multiple such devices are often delivering media signals (e.g., audio and/or video content) at the same time. In some cases, a person's PPM may receive a media signal from a media delivery device even if that person is not actively or intentionally consuming the media signal. Such an effect is commonly referred to as spillover because media delivered in one area spills over into another area occupied by monitored individuals who are not actively or intentionally consuming that media. In other cases, a person's PPM may receive media signals from multiple media delivery devices at the same time. For example, an adult watching the news via a television in the kitchen may be located near to a family room in which children are watching cartoons. In that case, the adult's PPM may receive stronger (e.g., code rich) audio/video content signals that overpower or hijack the sparse audio/video content (e.g., audio/video content having a relatively low code density) that the adult is actively and intentionally consuming. As a result, the adult's PPM (or a central facility receiving information from the PPM) may incorrectly determine that the adult is watching cartoons. Still further, other common difficulties such as varying volume levels, varying audio/video content type (e.g., sparse, medium, rich, etc.), varying household transmission characteristics due to open/closed doors, movement of furniture, etc. often lead to inaccurate media consumption measurements by PPM's.